Upgrade and Migration

[Carson Gaspar]

Ben Carter wrote:

> If you use rsync, you have to stop everything until that finishes, 
> possibly reconstruct all mailboxes, maybe fix some other things before 
> giving people their mail functionality back and allowing mail delivery 
> to resume.

That's just silly. If you're going to use rsync to migrate data, you do 
at least one rsync while the source data is live. More than one if the 
initial sync takes a long time. Then you go offline, do a final sync 
(which should be very fast), and bring the new data store online.

You have to do the _exact_ same thing with imapsync, unless you want to 
lose email.

> Also, the ACL format in the mailboxes file might be different between 
> these 2 Cyrus versions.

Might be, but I don't think it is.

> If you use the protocol to move the data, you don't have to worry 
> about any data structure differences etc.  You also can re-arrange 
> your partitions and so on.  Plus it re-calculates all quota usage as 
> imapsync APPENDs the messages during the migration.

All true, except to the best of my knowledge none of this (except 
repartitioning, which the OP didn't mention) matters for cyrus imapd - 
it will Just Work(tm) on your old data store. The only exceptions are 
database format changes (if you use bdb and you've revved the library 
version, for example), and sieve compiled bytecode.

And why do you care about quota re-calculation? The existing quota data 
should be correct.

-- 
Carson